MACOMB COUNTY, Mich. – West Nile virus has been detected in two samples of mosquitoes gathered in Macomb County.
“This discovery by our surveillance team is important because it lets us know that this season’s mosquitoes are now carrying the virus -- which could spread to humans,” said Andrew Cox, Director/Health Officer at the Macomb County Health Department. “We encourage everyone to take steps to prevent mosquito bites to the greatest extent possible.”
Last month, the virus was detected in a blood donation from an Oakland County resident. The donor had no symptoms of illness and it was found during routine screening of the blood. The screening is to help ensure the safety of the blood supply in Michigan.
Donations that test positive for the virus do not enter the blood supply. In 2021, the virus was detected in seven Michigan blood donors.
“We want to remind residents of Michigan that mosquito season is not over and it only takes one bite from an infected mosquito to cause a severe illness,” said Dr. Natasha Bagdasarian, MDHHS chief medical executive. “Take precautions such as using insect repellent and wearing long-sleeve shirts and long pants when outdoors during times when mosquitoes are active.”
What is West Nile virus?
Most people who become infected with WNV do not develop any symptoms. When people do become ill symptoms include headache, body aches, joint pains, vomiting, diarrhea or rash. Most people with that type of WNV recover completely.
Less than 1% of people infected will develop a serious neurologic illness. Symptoms include headache, high fever, neck stiffness, disorientation, coma, tremors, seizures or paralysis.
It’s transmitted through the bite of a mosquito that has picked up the virus by feeding on an infected bird. Symptoms appear three to 15 days after the bite of an infected mosquito.
Where has the virus been found in 2022?
The virus has been found in mosquitoes collected in Iosco, Arenac, Huron, Genesee and Kent counties, as well as birds collected in Bay and Shiawassee counties. This is the first human case reported this year.
Preventing mosquito bites
Mosquitoes aren’t just obnoxious, they also carry the risk of spreading diseases to people and animals.
“Whether you use an insect repellent or insecticide, always remember to read and follow all label directions,” added Verhougstraete. “The label is the law.”
So what can you do to prevent bites? Michigan officials suggest taking the following steps:
- When used as directed, Environmental Protection Agency (EPA)-registered insect repellents with one of the active ingredients below are proven safe and effective, even for pregnant and breastfeeding women: DEET, Picaridin (known as KBR 3023 and icaridin outside the US), IR3535, Oil of lemon eucalyptus (OLE), Para-menthane-diol (PMD), and 2-undecanone.
- Wear light-colored, long-sleeved shirts and long pants when outdoors. Apply insect repellent to clothing to help prevent bites.
- Maintain window and door screening to help keep mosquitoes outside.
- Empty water from mosquito breeding sites around the home, such as buckets, unused kiddie pools, old tires or similar sites where mosquitoes lay eggs.
- You could also hire a mosquito control business. Mosquito control businesses are required to be licensed to apply pesticides in Michigan. A list of Michigan firms licensed to apply pesticides is available online.
Mosquitoes lay eggs in or near standing water
Mosquitoes need standing water to reproduce. That’s why you should empty, scrub or cover any items that hold water.
Standing water is often found in old tires, buckets, planters, toys, pools, birdbaths, flower pot saucers or trash containers.
Mosquitoes can complete their life cycle in about a week. The CDC recommends using an outdoor insect spray made to kill adult mosquitoes. Mosquitoes are often found in dark, humid areas.
Can’t remove standing water? Larvicides are an option
If you’re unable to remove the standing water where you live then you’ve got one other option: Larvicides.
Larvicides work by killing mosquito larvae and pupae before they grow into pesky adults. According to the CDC, if you use larvicides correctly they do not harm people, pets or the environment.
Larvicides come in liquids, tablets, bits, pellets, granules and briquettes. You use them by applying them where mosquitoes lay eggs (that means anywhere that holds standing water). That can include buckets and rain barrels, fountains, gutters or downspouts, non-chlorinated swimming pools, pool covers that collect water, tires and tree holes.
Use larvicides to treat standing water that will not be used for drinking and cannot be covered, dumped or removed.